Participants swallow an oral dose of calcium containing an isotopic tracer. None of the participants wants to have needles stuck in them more than once. So you recruit 40 participants, and randomly...

Participants swallow an oral dose of calcium containing an isotopic tracer. None of the participants wants to have needles stuck in them more than once. So you recruit 40 participants, and randomly select eight to have samples drawn at 15 minutes, another eight to have samples drawn at 30 minutes, and so on at 45, 60, and 90 minutes. Does the typical amount of tracer in the bloodstream increase with time?